[camerax] Explicitly remove READ_EXTERNAL_STORAGE permission

[camsim99]

Specifies that READ_EXTERNAL_STORAGE permission should not be implied from WRITE_EXTERNAL_STORAGE and thus removed from any merged manifests.

Fixes flutter/flutter#131116.

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[rohansohonee1]

The following change causes this permission to be removed from any merged manifests. So was this the intended behavior?

Because this change gives an issue i.e if another plugin defines this permission of READ_EXTERNAL_STORAGE then it also gets removed from the merged manifest.

Eg: Using this plugin along with file_picker plugin.
file_picker requires this permission & it has been defined in it's manifest file as following:

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" android:maxSdkVersion="32"/>

In the merged manifest logs it rejects the file_picker permission.

uses-permission#android.permission.READ_EXTERNAL_STORAGE
ADDED from [:camera_android_camerax] /Users/appleapple/StudioProjects/file_picker_api_30_issue/build/camera_android_camerax/intermediates/merged_manifest/debug/AndroidManifest.xml:17:5-19:31
REJECTED from [:file_picker] /Users/appleapple/StudioProjects/file_picker_api_30_issue/build/file_picker/intermediates/merged_manifest/debug/AndroidManifest.xml:9:5-11:38
	tools:node
		ADDED from [:camera_android_camerax] /Users/appleapple/StudioProjects/file_picker_api_30_issue/build/camera_android_camerax/intermediates/merged_manifest/debug/AndroidManifest.xml:19:9-28
	android:name
		ADDED from [:camera_android_camerax] /Users/appleapple/StudioProjects/file_picker_api_30_issue/build/camera_android_camerax/intermediates/merged_manifest/debug/AndroidManifest.xml:18:9-64

@camsim99
Please let me know if I am missing something?